The Fourth International Dense Deposit Disease (DDD) Focus Group Meeting will be held in Leiden, The Netherlands on August 20th, 2011, immediately before the 13th European Meeting on Complement in Human Disease. This R13 wil be used to support graduate students, junior research scientists and junior faculty from North America who will attend this meeting. The aims and objectives of the Fourth International DDD Focus Group Meeting are: 1. To present advances in our understanding of the pathophysiology of C3-glomerulopathies, which include DDD and primary glomerulonephritis with C3 deposits (GN-C3); 2. To present advances in testing capabilities and the possible impact of C3 nephritic factors (C3Nefs) and other antibodies such as factor H autoantibodies (FHAA) and factor B autoantibodies (FBAA) in DDD; 3. To present genetic studies of DDD and discuss whether genetic data can be used to predict clinical outcome; 4. To evaluate the role of anti-complement therapies,such as eculizumab, in DDD. These aims and objectives are a logical extension of the prior three international conferences on DDD and will be achieved by: 1. Bringing together clinicians and basic scientists with expertise in complement; nephropathologists with expertise in DDD;clinical nephrologists with expertise in glomerulonephritis and clinical trials;human geneticists with expertise in DDD;and biochemists with expertise in glycosaminoglycans and the glomerular basement membrane (GBM); 2. Focusing on the pathogenic mechanisms that lead to DDD, with special emphasis on recent discoveries that implicate breakdown products of both C3b and the terminal complement cascade in the formation of the dense deposits; 3. Evaluating the clinical relevance of C3Nefs, FHAA and FBAA in DDD; 4. Presenting genetic advances in our understanding of DDD as a complex disease, including studies that have evaluated coding sequence of all complement genes in a large cohort of DDD patients; 5. Reviewing the current status of eculizumab in the treatment of DDD; 6. Presenting data on other anti-complement therapeutics as treatments for DDD; 7. Laying the groundwork for investigators meetings to plan a European/North American DDD clinical trail. The outcome of the Fourth DDD Focus Group Meeting may be published. Of note, after two of the three prior meetings, consensus statements were published in the Journal of the American Society of Nephrology (Appel et al., 2005;Smith et al., 2007) and have impacted the care of patients with DDD (see Appendix). PUBLIC HEALTH RELEVANCE: This grant is to support graduate students, junior research scientists and junior faculty from North America who will attend the Fourth DDD Focus Group Meeting to be held August 20th in Leiden, The Netherlands. These persons will also attend the 13th European Meeting on Complement in Human Disease immediately following the DDD conference.